1. Field of the Invention
The present invention relates to a device for cleaning a pipeline or other conduit by removing dirt, scale, and/or extraneous matter from the inner wall of the pipeline. More particularly, the present invention relates to a polyurethane spring which is used to support the cleaning device against the inner wall of the pipeline.
2. Prior Art
Conventional devices of the type used to clean the inner wall of a pipeline generally include a body adapted to be moved longitudinally through the pipeline and a series of scraper elements mounted on the body for engaging the inner wall of the pipeline as the body is so moved. One or more cups may also be mounted on the body for sealably engaging the pipeline wall so that the body may be propelled through the pipeline by means of fluid pressure behind the cups.
The scraping elements may comprise brushes with stiff bristles, blades disposed at an angle with respect to the axis of the body, or a combination thereof. In any case the scraping elements are tightly urged against the pipeline wall and are arranged about the body so as to scrape the entire circumference of the pipeline wall during a single pass of the device. In the past, the scraping elements such as the brushes with stiff bristles, have been mounted on the body by means of leaf springs which urge the brushes against the inner wall of the pipeline. The present invention involves the substitution of a polyurethane spring for the leaf spring heretofore employed.
A patentability search was conducted on the present invention and the following references were uncovered in the search:
Patent No. Inventor Dated 2,957,189 Nelson Oct. 25, 1960 3,576,043 Zongker Apr. 27, 1971 3,604,041 Ver Nooy Sept. 14, 1971 5,052,652 Sevilleja et al Oct. 1, 1991 5,208,936 Campbell May 11, 1993 5,280,890 Wydra Jan. 25, 1994 5,326,083 Wydra et al Jul. 5, 1994 UK2,229,247 A Kershaw Sept. 19, 1990 RU420,356 Petr Prod Aug. 26, 1974 RU1574289-A Oil Product June 30, 1990
Russian Patent No. 420,356, describes a hollow shaft and cleaning elements forming a hinged parallelogram. A cleaning brush is mounted on a parallelogram type structure which is metallic. The assembly is urged against the side of the pipe by means of an arrangement involving a central shaft, springs, etc.
Sevilleja et al, U.S. Pat. No. 5,052,652, is relevant only in that it discloses a damping device which has a rectangular prismatic shape with rubber inserts. There is nothing in this patent to suggest that the damping device could be employed in a cleaning pig to urge the cleaning devices against the pipeline wall.
Zongker U.S. Pat. No. 3,576,043, in column 3, lines 27-34, talks about cups, bumpers, and scraper ribs being made of polyurethane. However, the spring members 17 are still described as "bowed leaf springs".
Nelson U.S. Pat. No. 2,975,189 shows a parallelogram type arrangement for the cleaning brushes. Nevertheless, the cleaning brushes are still spring mounted by means of metallic springs.
Ver Nooy, U.S. Pat. No. 3,604,041, is deemed pertinent in that the base, blade and rod are described a being made of urethane. Nevertheless, the spring element 15 is still a leaf spring.
U.S. Pat. No. 5,280,890 to Wydra shows a compression spring which can be made of an elastomer which is not specifically disclosed as a polyurethane, but which is believed to be an equivalent. There is no showing that his elastometric compression spring could be used to urge the cleaning brushes of a cleaning pig against the inner wall of the pipeline.
U.S. Pat. No. 5,326,083, also issued to Wydra, shows a compression spring formed of an elastomer. The same comments hold true as with respect to the last Wydra patent discussed.
Russian Patent No. 1574289-A, shows a parallelogram type arrangement. This reference still lacks the teachings of a polyurethane spring.
UK Patent No. 2 229 247 A, shows a polyurethane disc 12 supporting a plurality of cleaning fingers 19, capable of scraping scale or wax 11 from the inside of a pipeline 10. The cleaning fingers 19 appear to be made of metal.